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phone apps for star charts

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#1 jmillsbss

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Posted 09 September 2019 - 09:11 AM

Hey all  -   I have been using SkEye as my primary chart resource for about 4 months and it's been remarkably helpful.  It doesn't overwhelm with every single star or object in the sky but it can be set up to show as many or as few objects as you want.  Also, it's very easy to option in or out any number of parameters.  Just super helpful for the new stargazer.

 

It's got a tracking option that allows you to attach it to a scope, make a 2-star alignment and suddenly now you have a push-to scope.  On the surface, this is awesome.  A free app that gives you an upgrade worth more than the cost of your scope!

 

BUT - there's always a but.... although I've had modest success, it always seems to experience an issue, "WARNING: Strange Magnetic Field Present".

 

The instruction is to restart your phone, wave the phone in a "figure 8", re-attach to OTA and repeat another alignment procedure.  That'll work for a bit but then you get the same message and lose the alignment.  Upon further digging, turns out the strange magnetic field is caused by metal objects....It says do not attach to metal structures....

 

MY ENTIRE XT10 TELESCOPE IS METAL!!!!!   Would you have me attach it to the fiber-board rocker box?!?  No, of course not.  It's gotta be attached to the OTA and oriented toward the same general line of sight as your telescope.

 

Oh, I already know.  "Jay, you can't expect an app on your (cheaper than most) phone to perform as a DSC setup or GoTo mount."

 

I know.  But it does actually work. It's got a bit of a lag, but I can set it up and point it at a known object (using my red dot finder) and it eventually jogs the display to the object on the screen.  Inevitably it experiences another magnetosphere error.  Perhaps it's just my 3 year-old LG p.o.s. phone...

 

I just wonder if any of you have ever used such things with any success?  I wanted to know how you shielded your phone/tablet to avoid such errors.  Perhaps you mounted it on some sort of material that's non-conductive or some other solution?   Has anyone ever tried such a thing with an elevated mount like the one I use with my finderscope?   I have an extra single pad mount.

 

Maybe others have better apps or another way to get this one to work better?

 

I'm sure someone's gonna say, "It's a phone. Give it up."  but don't be that guy!  Thanks again for all your good help!!!   Jay


Edited by jmillsbss, 09 September 2019 - 09:18 AM.


#2 sg6

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Posted 09 September 2019 - 09:23 AM

It is not really SkyEye but the phone, they used magnetic systems and as you say the scope is metal and so influences it. Not a lot you can do really. Maybe lostae the phone further from the metal of the scope.

 

I have a similar problem in that the app on my tablet uses magnetic sensors. Now why when it has a perfectly good GPS system is beyond me. At least allow me to select GPS only. Really stupid thing was the protective case had a magnetic clasp to hold it closed. That really upset the thing.

 

Not sure if Skysafari would do what you want and be better, the idea/hope is that Skysafari uses the GPS only and ignores magnetic. Would make sense. The Plus version is all you need in terms of features and doesn't cost a great deal. The Pro is more in $ but maybe "worse" is that it is big so needs processor and memory.


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#3 Jon Isaacs

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Posted 09 September 2019 - 09:38 AM

It's not even the metal scope, it's the compass in the phone/tablet.  A compass accurate to 1 degree costs a bunch of money and must be calibrated in place.

 

GPS does not provide orientation information, just location. It tells what direction you are moving by measuring what direction you are moving.  

 

A digital level and a bit of star hopping does work.  The digital level is accurate to about 0.1 degree.  You only need to know which side of the object you're on and then do a sweep.. Scope needs to be level.

 

Jon


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#4 Sean Wood

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Posted 09 September 2019 - 11:54 AM

I used SkEye for a bit before I decided to learn to star hop. I was getting the magnetic warning and decided to take my OTA to the machine shop I work at and run it over our industrial electromagnet demagnetizer. That did the trick for me. The warnings went away and the accuracy was a smidgen better. If you don't have access to a industrial demag-er you can do the same thing with an old school bulk tape eraser. Remove any electronics from the OTA or they may get damaged. You'll want to wrap the eraser in a towel to protect your OTA finish. Turn the eraser on and run it from end to end in a straght line the length of the OTA, once you make a pass Roll the OTA about 1-1/2 times the width of the eraser and go back the other way without turning the eraser. Try not to wiggle the eraser around or turn it, keep it oriented the same way with each pass. Repeat till you get all the way around the OTA. Test to see if the tube is still magnetic. Rather than using Skeye I'd suggest any of the "metal detector" apps that in the play store. You may need to go over the tube again. Keep in mind this will be a temporary solution, It may revert back depending on the environment you use it in and how much abuse it receives. You WILL have to do it again at some point.



#5 Keith Rivich

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Posted 09 September 2019 - 01:40 PM

This past Saturday night I set up at an unfamiliar location. Needing to plop my platform down during the daylight I used my phone to find north. Fast forward to night and I found I was around 15 deg (east) off of polaris. I had a friend bring his phone and he showed north a little west of polaris. I third phone joined us and her north was between mine and the 2nd phone!

 

I understand the science but it seems the magnetic deviation could be programmed into the phones and location services would provide the, well, location to use the correct offset. Anyone know an app that actually uses this information?



#6 TelescopeGreg

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Posted 09 September 2019 - 10:13 PM

It also helps to "calibrate" the compass and other sensors in the phone.  With the app running, swing the phone around in a "figure 8" as if you're a 6 year old playing with his/her airplane.  Sometimes that works, or at least helps.  "Airplane noises" are optional.

 

Great app, by the way.  I use it also.


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#7 lambermo

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Posted 10 September 2019 - 12:07 PM

I use SkEye on a truss dobson. And I mount the phone halfway those trusses. The aluminium trusses do not distort earth's magnetic field. And the iron parts of the scope are apparently 'far away' enough for me.

I highly recommend this app. On low magnification power I always have the target object in view immediately.

Best to stay away from buildings and anything else that distorts the magnetic field, also give "gather your senses" from the same developer a try to test your magnetometer https://play.google....dip.sensegather

-- Hans



#8 jmillsbss

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Posted 26 September 2019 - 08:20 AM

I use SkEye on a truss dobson. And I mount the phone halfway those trusses. The aluminium trusses do not distort earth's magnetic field. And the iron parts of the scope are apparently 'far away' enough for me.

I highly recommend this app. On low magnification power I always have the target object in view immediately.

Best to stay away from buildings and anything else that distorts the magnetic field, also give "gather your senses" from the same developer a try to test your magnetometer https://play.google....dip.sensegather

-- Hans

Well the next scope upgrade will be a bigger aperture and there will be trusses!  I thought I might try a wooden block attached to the scope between the tube and the phone.  It cant hurt!



#9 NMBob

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Posted 26 September 2019 - 09:20 AM

You can't shield from magnetic fields (like you can with radio waves), but there are foils and plates that you can use to "channel" the field away from your phone. A band around the scope in the area of the phone may help.

 

http://www.lessemf.c...g-shld.html#276



#10 Jon Isaacs

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Posted 26 September 2019 - 10:43 AM

I have searched the internet for digital compasses accurate to +/- 1 degree. They are very expensive and require calibration in place. 

 

Cell phone and tablet compasses just don't have that kind of accuracy.. 

 

Jon




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